A building such as a skyscraper or an apartment has a stair hall which serves as an evacuation passage for allowing persons in the building to evacuate. In addition, a vestibule is present between an indoor space such as a living room and the stair hall, and a smoke control damper is installed in the vestibule. If fire occurs, an air current is supplied into the vestibule by means of a smoke control damper to form an air egress velocity toward the indoor space, which prevents smoke from flowing into the stair hall and allows persons in the building to safely evacuate through the stair hall. A system for installing a smoke control damper in a building and relevant construction regulations are disclosed in Korean Unexamined Patent Publication No. 10-2011-47742, and a conventional smoke control damper is disclosed in Korean Utility Model Registration No. 20-316848.
FIG. 1 is a schematic cross-sectional view showing a rotary switch blade 13 provided at a general smoke control damper, which is at a closed location, and FIG. 2 is a schematic cross-sectional view showing the rotary switch blade 13 which rotates and comes to an open location. As shown in FIGS. 1 and 2, the conventional smoke control damper includes a plurality of rotary switch blades 13 successively arranged in a row in the vertical direction. In the state depicted in FIG. 1, the rotary switch blades 13 are vertically located and close a blowing passage of the smoke control damper. In the state depicted in FIG. 2, the plurality of rotary switch blades 13 are at horizontal locations and open the blowing passage of the smoke control damper. In the state of FIG. 1 as described above, if the plurality of rotary switch blades 13 rotates by an operation of a motor and comes into horizontal locations, the blowing passage of the smoke control damper is opened as shown in FIG. 2. Therefore, an air current is blown through the blowing passage between the rotary switch blades 13, thereby forming an air egress velocity with respect to a shelter door which allows a person to move from an indoor space to a vestibule.
Therefore, in a conventional smoke control damper, all rotary switch blades 13 are kept in a horizontal or inclined state depending on the degree of rotation of the rotary switch blades 13, and accordingly an air current supplied to the vestibule has a specific direction through the blowing passage formed by a gap between the rotary switch blades 13. However, if the conventional smoke control damper for opening or closing the blowing passage by rotation of the plurality of rotary switch blades 13 is left unused for a long time, the rotary switch blades 13 may not easily rotate. If the rotary switch blades 13 do not rotate to a perfectly horizontal state as described above, the rotary switch blades 13 are in an inclined state, which also brings the blowing passage into an inclined state. In this case, an air egress velocity is not regularly formed at the shelter door.
In particular, in a conventional smoke control damper, the direction of the air egress velocity varies according to the direction toward the shelter door. In other words, the direction of the air egress velocity is different depending on whether the smoke control damper faces the shelter door or the smoke control damper is perpendicular to the shelter door. This is because the air current supplied to the vestibule through the blowing passage formed by a gap between the rotary switch blades 13 of the general smoke control damper has a specific direction. Due to such a direction of air current, the air egress velocity formed by the air current supplied through the blowing passage of the rotary switch blade 13 may not be formed to flow toward the shelter door but be formed to flow from the shelter door to the vestibule, which makes smoke spread more to the stair hall and even presses the shelter door not to be opened toward the vestibule.
Therefore, when installing the conventional smoke control damper at the vestibule, the location of a shelter door should be taken into consideration, and the building should be designed in consideration of relations between the smoke control damper and the shelter door, which gives many limitations in an actual building designing work.